Histopathologic Features of Drug Reaction With Eosinophilia and Systemic Symptoms.

Abstract

Drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome is a severe cutaneous adverse reaction occurring 2 to 8 weeks after medication initiation. Diagnosis is clinical; RegiSCAR scoring includes biopsy "suggestive of DRESS," undefined in the literature. This study correlates DRESS dermatopathology, culprit drugs, disease course, and outcome severity compared with maculopapular drug reactions (MDR). Between 2014 and 2023, a retrospective cohort study at a tertiary care institute reviewed 55 patients with DRESS, assessing demographics, culprit drug, illness course, and histopathology. Biopsies of 15 patients with DRESS and 15 MDR patients were graded by a predefined histopathological scoring system. Statistical analysis (significant P -value<0.05) included the Fisher exact probability, ANOVA, and correlation tests. Among 55 patients with DRESS (mean age 50.13, 28 female/27 male), 15 (mean age 50.4, 7 female/8 male) had diagnostic biopsies. Compared with MDR patients, patients with DRESS exhibited significantly more interface dermatitis ( P = 0.04), lichenoid dermatitis ( P = 0.0007), pigment incontinence ( P = 0.04), and periadnexal interface dermatitis ( P = 0.002). MDR biopsies displayed perivascular inflammation and higher eosinophils than DRESS, trending toward significance. Key histopathologic features are interface dermatitis, periadnexal interface dermatitis, lichenoid dermatitis, pigment incontinence, and neutrophils dominance over eosinophils indicate DRESS clinically.